1. Field of the Invention
The present invention is generally related to a light emitting module and process thereof, and more particularly, a light emitting diode used as a lighting source for the light emitting module and process thereof.
2. Description of Related Art
Over recent years the technology behind light emitting diodes has developed rapidly, especially compared to that of traditional Incandescent Lamps. HP LEDs (High-power light emitting diodes) are seen as better illumination devices because the over greater power saving, a longer usage life, high durability and faster responding speeds. Because of these advantages, light emitting diodes have become more common in different fields, such as the general lighting market, public works and for automobiles. Further facilitating these are other markets that require this kind of light emitting diodes which are continuing to grow.
However, a big problem is how to overcome the usage life being shortened and efficiency reduced due to excessive temperatures. Please refer to FIG. 1 which illustrates a structural cross-sectional view for a traditional panel type light emitting module. Shown in FIG. 1 is a printed circuit board 3 attached to a metal substrate 1 by an insulation colloid 30 that prevents a short circuit from occurring. The metal substrate 1 can be built with a fillister to adhere the die(s) of light emitting diode 2 directly. Alternatively, the light emitting diode 2 is adhered to the metal substrate 1 by a silver epoxy 20 to conduct heat. Finally, conductive wires 4 are connected between the light emitting diode 2 and the printed circuit board 3 for electrical connection.
Please refer to FIG. 2 which illustrates another structural cross-sectional view for a traditional light emitting module. FIG. 2 shows one kind of lead frame type light emitting diode module. A bearing base 5 is disposed within an insulation housing 70 to carry a light emitting diode 2. Furthermore, the light emitting diode 2 is adhered to the bearing base 5 by a silver epoxy 20. Conductive wires 4 electronically connect the light emitting diode 2 to a first lead frame 61 and a second lead frame 62 separately. The bearing base, first lead frame 61 and the second lead frame 62 are prevented from electronically connecting by the insulation housing 70.
The most of above mentioned conventional light emitting modules are using silver epoxy 20 as a heat conduction medium. However, for conducting heat for a high power light emitting diode 2, the silver epoxy 20 is still deficient, and that makes the light emitting diode 2 heat dissipation comparatively slow. Even after installing additional heat dissipation mediums (such as a Heat Sink) under the metal substrate 1 or the bearing base 5, it is still unable to dissipate more heat because the actual heat energy is unable to be conducted to the heat dissipation medium effectively. For that reason, operators sometimes misconceive that the temperature of the overall light emitting module is not very high and assumes the light emitting diode 2 is still able to work at safety condition. However, in reality, the light emitting diode 2 itself is in danger of being damaged, because the heat energy is unable to be conducted.
In order to improve the heat dissipation performance, silver epoxy 20 with high thermal conductivity can be used, however it will be too expensive to build a reasonably low cost commercial product. Improved high thermal conductivity silver epoxy 20 is also difficult to preserve and solidifies easily as general silver epoxy 20. Moreover, if it is used on a higher power LED module, it is still not good enough to conduct heat energy effectively and quickly.